As August comes to a close, pumpkin spice season is officially in full swing. Dolly Parton Pumpkin Spice Cookie Mix, produced in collaboration with Duncan Hines, is now available online, through major retailers including Walmart and Kroger, and via Instacart. To make the cinnamon-scented cookies — which, according to the box, also contain “pumpkin puree solids” for real fall flavor …